The basic idea is that Kant's philosophy needs to be balanced with an equal and opposite poetics. His "transcendental doctrine of elements" needs a "pangrammatical supplement", and that's just the immanent program of totality. (I like that analogy—a program is to power what a doctrine [Lehre] is to knowledge—which occurred to me when thinking about Williams and Wittgenstein earlier this month.)

Remember that imagination is pangrammatically analogous only to itself. It's "in the middle" between the "the media of immediacy", i.e., intuitions and institutions. The image belongs to neither philosophy nor poetry. This means that imagination is also the faculty for representing a subject even without its presence in institution. Let's try now to translate the following passage from Kant Critique of Pure Reason, specifically, a sentence from §24 of the "Transcendental Doctrine of Elemements", into the terms of the immanent program of totality. Here's Kant (in Guyer and Wood's translation), which follows immediately the definition of imagination I've quoted in the epigraph:

Now since all of our intuition is sensible, the imagination, on account of the subjective conditions under which alone it can give a corresponding intuition to the concepts of understanding, belongs to sensibility; but insofar as its synthesis is still an exercise of spontaneity, which is determining and not, like sense, merely determinable, and can thus determine the form of sense a priori in accordance with the unity of apperception, the imagination is to this extent a faculty for determining the sensibility a priori, and its synthesis of intuitions, in accordance with the categories, must be the transcendental synthesis of the imagination, which is an effect of the understanding on sensibility and its first application (and at the same time the ground of all others) to objects of the intuition that is possible for us. (KRV B151-2)

I won't here explain how it's done (I'm sure it's largely obvious), but here's a draft of the analogous passage in the Crisis of Raw Passion:

Now since all institutions motivate, the imagination, on account of the objective conditions under which alone it can take a corresponding institution for the emotions of obedience, belongs to motivation; but insofar as its analysis is still an exercise of discipline, which is determining and not, like motive, merely determinable, and can thus determine the content of motive a posteriori in accordance with the multiplicity of apperception, the imagination is to this extent a faculty for determining motivations a posteriori, and its analysis of institutions, in accordance with the dispositions, must be the immanent analysis of the imagination, which is a cause of obedience to motivation and its first application (and at the same time the ground of all others) to subjects of institution that is necessary for stuff.

I promise you there is method in that madness, albeit no doubt along with a few imprecisions and errors. I'll try to explain in another post.